1. Field of the Invention
The invention relates to an internal combustion engine with exhaust-gas turbocharging which is connected to two exhaust-gas turbochargers.
2. Discussion of Background
German Utility Model 7,004,611 has disclosed an internal combustion engine on which two exhaust-gas turbochargers of identical construction are secured by means of support elements. They guide the exhaust gas flowing out in opposite directions into a simple turbine outflow casing arranged as a connecting element between them. However, this solution has the disadvantage that the exhaust gases are carried away relatively rapidly and hence without the possibility of recovering the energy of the exhaust gas.
DE-C2-31 08 288 has disclosed an internal combustion engine which likewise has two exhaust-gas turbochargers arranged opposite one another in the direction of flow and each having a radial compressor and a radial turbine, said internal combustion engine eliminating this disadvantage. For this purpose a number of components of a design favorable in terms of flow, which reduce the outflow velocity of the exhaust gases and thus ensure relatively high recovery of specific kinetic energy, are arranged in the common turbine outflow casing.
However, more recent exhaust-gas turbochargers operate with considerably higher boosting, smaller radial turbines producing exhaust-gas flows with a higher specific kinetic energy which is then converted into a higher static pressure. In radial turbines of this kind, the direction of rotation of the exhaust gases is opposite to the direction of rotation of the rotor of the turbine.
They produce a swirl in the exhaust gases resulting, for its part, in locally high flow velocities of the exhaust gases.
An apparatus in accordance with DE-C2-31 08 288, i.e. in particular the components designed in a manner favorable in terms of flow arranged in the turbine outflow casing, cannot be used for exhaust-gas turbochargers with considerably higher boosting without prejudicing the intended effect of, flow retardation with an increase in the static pressure. If this solution were used, the efficiency of the exhaust-gas turbocharger would thus in fact be reduced.